The present invention relates generally to a magnetic head for magnetically recording and reproducing signals on and/or from a magnetic recording medium such as magnetic tape and a method for making such a magnetic head, wherein non-magnetic zinc ferrite is used as a gap-defining spacer material.
Various types of magnetic heads have been developed. Of these, a magnetic head in which glass bodies are used for defining a magnetic gap thereof is general which further includes first and second magnetic core halves each being made of, for example, Mn-Zn single crystal ferrite. The first and second magnetic core halves are held in abutment against each other so as to form the magnetic gap. The magnetic gap is occupied by a gap-defining spacer material such as SiO.sub.2 so that it is sandwiched between the first and second core halves and the gap-defining spacer is welded to them by means of the glass-welding method.
However, according to the glass-welding method, the welding is performed using glass melted by heating to a temperature of about 700.degree. C., with the results that the glass and SiO.sub.2 diffuse and penetrate into the ferrite cores on the welding process. The diffusion and penetration result in a substantial increase in gap-length, worsening magnetic head performance, and further the difference of coefficient of thermal expansion therebetween sometimes causes breakage of the magnetic head and deterioration of magnetic permeability.
On the other hand, Japanese Patent Provisional Publication No. 58-185437 discloses a magnetic head wherein non-magnetic zinc ferrite is employed as a gap-defining spacer material. This magnetic head not only eliminates the above-noted problems but also provides various advantages s including increase in workability. However, the prior art magnetic head has a structure in which the gap-defining spacer is interposed between the magnetic core halves and bonded thereto by a bonding material. One of problem with such a head structure is that there are differences in physical properties between the bonding material and the magnetic core halves or gap-defining spacer, thus resulting in the occurrence of strain between the spacer and magnetic cores and deterioration of magnetic characteristics. Furthermore, dispersion in wear resistance of the tape-contact surface thereof occurs at the joint portions between the gap-defining spacer and magnetic cores, thereby shortening the usable life time of the magnetic head because of a partial wear. Therefore, a further improvement will be required from a viewpoint of increase in durability of the magnetic head, preventing the magnetic characteristics from being deteriorated, and increase in running properties of the magnetic head.